I actually played 4E for about a year and a half before coming to Pathfinder, so I'm not sure how I qualify, but here's my two cents anyway.
• Point buy method as the standard for ability score generation. I love that you have to make a decision to have an 18 instead of whining to a DM to let you reroll until you get 18's. I've been doing point buy exclusively since 2001 or so... But I love how it's the standard now.
• Fixed hit points. Mainly for the same reasons that I like the point buy method for ability scores.
• Static defenses. I really like the idea that the initiator of an action is the only one rolling dice to determine its success. It seems very intuitive to me.
• Some degree of self-healing. I like the second wind thing in theory, although I think it needs some work.
• The consolidation of certain skills, such as Perception and Stealth.
Now, the things I don't like about 4E are considerably more numerous... But I'll gladly defer my expression of my opinions on that in respect to the original poster.
(I am perplexed by those who cite "terrain matters" as some kind of 4E thing, since terrain is a regular and important feature of my 3.5 games. YMMV, I guess.)
Yeah, this is one of the things that really made me scratch my head when 4E was coming around. I read
Sun Tzu's Art of War when I was fourteen or so, when 2E was gearing up, and assumed that other DMs were interested in military philosophy. I fondly remember kobolds and goblins with superior tactics beating the snot out of vastly superior parties of PCs through smart use of the terrain (they certainly couldn't rely on their AC and hit points, after all).
Arguably, several historical battles were studies entirely in how small groups used terrain to their advantage against a supposedly superior force (such as the battle of Thermopylae, various battles at Mount Gilboa, or Caesar's assaults against the Gauls). It's always seemed odd to me that more D&D players aren't interested in historical battles.
In this respect, 4E's emphasis on terrain doesn't seem like a huge leap forward in game design so much as the game designers catching up to how I've been playing the game for years.